Power systems often include a power converter that is configured to convert direct current (DC) power into a suitable power for application to a load, such as a generator, motor, electrical grid, or other suitable load. For instance, a power generation system can include a power converter for producing alternating current (AC) power at a grid frequency (e.g. 60/50 Hz) suitable for application to an electrical grid. In solar or batter energy systems, the solar or battery source can provide direct current power to the power converter, which can then be converted to suitable AC output power for the electrical grid. In applications requiring AC to AC conversion, such as wind energy applications, the power converter can include two stages to provide AC to DC to AC conversion.
To provide increased output power capability, a power converter can include a plurality of bridge circuits coupled in parallel with one another. Each bridge circuit can include a plurality of switching elements (e.g. insulated gate bipolar transistors (IGBTs)). The pulse-width-modulation (PWM) of the switching elements can be controlled according to a desired switching pattern to provide a desired output of the power converter. Each switching element can further have an associated antiparallel diode.
The switching elements and antiparallel diodes can have a plurality of associated bond wires configured to couple the respective switching elements and antiparallel diodes to one or more other components on a power semiconductor module associated with the power converter. Such bond wires can become warn out over time due at least in part to variations in temperature associated with the power semiconductor module. In particular, such bond wires can rupture or lift off and become disconnected from the power semiconductor module, causing the remaining bond wires to dissipate heat.
Various techniques have been implemented for detecting bond wire failures. For instance, such conventional techniques include detection of variations in the collector-emitter voltage (Vice) of the associated IGBT to predict bond wire failure, detection of variations in parasitic gate capacitance of the IGBT to predict bond wire failure and other techniques. However, such techniques can be inefficient and/or difficult to implement.